Do hair dyes cause cancer?

It seems like the health debate regarding hair dyes and their relation to cancer has been around forever, so I decided to do a little digging. Here's what I found: the Canadian Cancer Society doesn't seem too concerned with the risk, as they point out in this article. The New York Times has also pointed out that there's no significant link, or as they put it, "no smoking gun."

Both sources acknowledge that an ingredient in hair dyes prior to the 1980's have been shown to present a larger risk than ones produced today, and that darker shades are more correlated with cancer than lighter ones. Dyes have been linked to both bladder cancer and Lymphoma, but not yet conclusively. All other info I found against hair dye seemed to be fairly outdated.

I know a lot of people who dye their hair and probably would continue to do so unless there were smoking-like warnings (the old 'vanity knows no cost' saying probably applies here). I'm fairly cautious with cancer warnings, but I don't think there's enough evidence to force me to live with my mousy-brown roots just yet. What do you think?